How to Cut a Boxed Heart Timber

[Jim_Rogers]

If you need to box the heart on the timbers, which is making the pith in the center of the beam on both ends this is how I do it.
You can do it by proper planning; you plan your last cut first. Now that sounds difficult but it really isn't.
First I load my logs with the small end or it's also called the top end of the log towards the trailer hitch or operator position. That way you can plan your cuts based on what you see from this the small end. Now to tell what size log you'll need for an 8x8, for example, take a framing square and measure across from 8" on one side to 8" on the other, diagonally and you'll see that you need an 11 3/8" diameter log. That is measuring inside the bark on the narrow end of the log. If you want your beams to be free of sap wood then inside the sap wood ring.
The next thing I do is load the log onto the sawmill. Once on the sawmill I mark the ends of the log with a lumber crayon to show a plus sign (+) with the lines crossing directly over the pith/heart of the tree, on both ends. These cross marks/hairs are your centers of the beam/log.
Now you need to level these to the table of the sawmill, and thereby leveling them to the sawblade. I do this with a framing square. Here is a shot of me doing this:



 
Now you see the red cross hairs and the one with the arrow on it? That is the first face we'll be sawing. The red arrow is just to remind me where face one is.
Next to the framing square is a little block of wood. This block is the offset from the frame of the sawmill to the table of the sawmill, to read the height of the pith you look at the square at the point where the top of the block is, when it's against the square. This will tell you the height of the heart/pith off the table.
You do this on both ends:



 
This is a shot of the big end being checked with the framing square
 
Now you know how high the heart/pith is off the table. Let's say that this small end is 7 1/2" off the table and because the log has a taper to it (that the small end is smaller, as most logs have a large end and a small end), and that the other big end is 9" off the table. You need to lift the small end up 1 1/2". But after you do this check the big end and make sure it doesn't tip down to 8" or so. If it does split the difference with the sawmill taper controls and level the log's heart/pith to whatever level it comes out to be.
Next, since you have the log level and having done that with the framing square you now know how high the heart/pith is off the table. In our example log we've said it is 7 1/2" so if you are going to produce an 8x8 and you want the heart/pith in the middle then the last cut on this face should only be 4" above the heart/pith or at 11 1/2". That's it don't cut any deeper or you'll be making your heart/pith off center. So set your sliding scale to finish your cuts at 11 1/2". If you're cutting one inch boards off your logs on the way to the 8x8 then put a 4 line on the sliding scale on 11 1/2" and then start cutting on any 4/4 line above 11 1/2" and finish this first face with your last cut at 11 1/2". Here is a shot of the sliding scale:



 
In the above picture the 4/4 scale is lined up on 11 1/2". This was just a shot to show how you can line up the sliding scale to whatever line you'd like to finish on.
 
After the first face is done, roll the log 90° and do the same thing again. That is level the log using the cross hair red lines and the framing square.
Here is a shot of side two lined up:


 
 
After you have lined up face two and figured your last cut on this face, and made all your cuts to the last cut spot you roll your log to face three.
On face three, no taper controls will be needed as this side has already been leveled. Now you set your sliding scale to finish at 8". Then cut boards until you're at 8". Next roll your log over to face number four and your scale is already set for 8" so don't move it and cut until your beam is done, by cutting face for down to 8".
That's it you've now got a boxed heart timber 8x8 and boards cut on the way to it.

Here is a shot of the boxed heart timber:




If you're cutting planks, like 2" stock you'll have to adjust your scale to make the cuts in the right places to do that.
If you have any questions about doing this procedure, write me and ask specific question.
Jim Rogers

[Engineer]

Jim,

Thanks for the great info on boxing the heart.  I'm going to be trying that for the first time this weekend, and I was trying to figure out how to measure down for  the final cut and still get 4/4 boards without making the last cut 1/4" or less.  Now I know.  The sliding scale thingy is the key.  

Jon E

[Ed_K]

 Thanks Jim, That helps a lot. On 8" should I cut it to 8 1/8" for shrinkage, I'm never clear on how much extra.
Ed

[Jim_Rogers]

A word of caution.

You can't always cut to the finish size on a face, if the log has stress in it.
You'll have to read the log and watch the lumber coming off the cant and see what's happening.
If the log has stress in it you'll have to leave one or two boards on that face and roll the log to another face and relieve the stress over there first.
The above example was with a straight grained eastern white pine log and it had very little stress in it that I remember.
If you're cutting hardwood beams you'll have to learn to "read" the log and see what's happening with the lumber as it's being cut. If the boards shifts right, left, lifts at the start end or bows up in the middle, it has stress in it. And you might have to leave several boards on a face and come back to that face later and finish it after you've relieved the stress on the opposite side of the log.
If you do leave one or two boards on a face and roll to the opposite face to relieve the stress you have to remember to correctly set you sliding scale (if your sawmill has one, like the woodmizer scale) to finish at 8" but stop cutting one or two boards above that 8" mark on the opposite face and then finish to 8" on the first face where you left them before. Sometimes I write a 1 or 2 on the end of the log near the face that isn't finished to remind me that there is one or two boards left on that face. It's so easy to loose track of where you are on a face as you are working other faces at the same time.

Ed_K:
I personally don't leave any extra on the log for shrinkage. In my timber framing projects I use the square rule method of joint layout which compensates for under-size timbers.
But if you want to then just adjust your sliding scale so that you're beam will finish at the larger size you want (if your sawmill has a sliding scale).
If you're sawmill doesn't have a sliding scale come back to your computer and make up a chart and print it out and keep it on a clip board near your sawing station. Then when you need to remember where to make your cuts you can just look down at your clipboard and see the locations where you need to make your cuts.
Here is a chart I made up for cutting 2" decking on my way down to smaller timbers. I printed up this chart and wrapped it in clear shipping tape onto a piece of thin cardboard and keep it clipped onto my sawmill near my scale so that I can just look at the chart and adjust my sawmill to cut at the right height to finish the log at the right size.





Good Luck with your milling of timbers.
Jim Rogers

[Ed_K]

 Jim,
 Good point on the stress. I tried to box a white pine 16' to a 6x6, when I got to the finish dim, it had a rise in the middle of 9/16. So I turned it on its side and made 2x6 s  :D. Oh well I got plenty more where that came from  8) 8) 8).
 Thanks for the chart, I copied it. I have a line up for 4/4 on the wall next to the saw, and 5/4 wrote on to mill itself  ;).I never even thought about adding extra, till I tailed for Woodchuck 55. Oh, I have a wheel on my mill to read height, I may try to add a slider on, now that I understand what its for.
 Ed K

[DanG]

DanG it, Jim!  You running low on RustReaper, and trying to win another batch?  That was a great tutorial on sawing beams.  Though my mill works entirely different, the layout and marking would be very similar to what you showed. Thanks for sharing your knowledge and experience.

[Jim_Rogers]

To those of you who don't have sliding scales on your mill, if you can make up something to use, pass it on to your mill manufacturer, maybe help pay you something for the idea.
Also you could post it here for others who have the same type of mill as you.
When I'm sawing and have a weird size log and need to figure where to make my cuts I take my construction calculator to the sawmill work station, and keep it near my clipboard. Then when I have to add several 1 1/8" pieces to the finish size to get my starting point, I use the calculator to add them for me and it works good for a quick chart.
I left it home for the last two day and had to do it the old fashioned way, in my head. I've got it here today.
DanG I don't believe they'll give me another prize for future posting. They should give it to others who have posted info on the forum. They could start an honorable mention class for second place tho.
Just an idea.

Ed_K:
I make up charts or scales for all the different sizes I've cut, and print them when I need them. I've made several and use them as the occasion arises for cutting different thickness lumber.

Jim Rogers

[Larry]

I just took a quick glance at this thread when Jim first posted it.  I have boxed the heart a few times – just take a nice round top log and saw it to the cant.  Was perfectly happy if the pith came out somewhere close to the center. :

Sooooo I'm at the mill with a bunch of butt oak logs with the typical swell.  Figured I would taper saw for grade and when I got to the cant I would box the heart in 6X6's for the little timber frame I want to build.  First log I get close to the 6X6 and measure with the tape measure for half an hour.  The tape measure wasn't calibrated because the pith ran out of the cant about a foot from the end. :(  Second log I measured for maybe an hour and made a couple of test cuts just to make sure the tape was working.  Got the pith centered but thought with this rate of production the snow is going to be flying by the time I get done. :(  Came in and reread this thread in earnest.  Took off my dunce cap and put on my thinking cap.  Went back to my four poster mill and cut a couple of boards the same height as the bunks.  Laid them on the rails right under the end of the log so I could quickly get a measurement to the pith and adjust the toe board.  Wasn't long until I could take two measurements to the pith, adjust the toe board, and set the sliding scale.  Had the pith centered within 1/4" and it was only taking about 5 minutes per timber. 8)

Thanks Jim for taking the time to put your post together. 8) 8) 8)

I got the timbers on sticks.  Thought I would ask before I make another stupid mistake.  Do you leave any space between the timbers as they dry? :P

[Jim_Rogers]

I leave a space between all timbers for air flow. That way air can dry all faces hopefully evenly.
I'm glad you figured out how to save part of your good grade log for a timber after you've milled off the outer boards.
Working a cant that's wedge shaped back to a 6x6 can be a challenge.
Good luck with your project, and thanks for your comments I'm happy it worked out for you.
Jim Rogers

[Kirk_Allen]

Thanks for the lesson.  

Thank God for Accuset! ;D

When it goes down, I now know how to do it the old fasion way, which is good to know!